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Long the king of the vegetable garden plot, the tasty tomato (Lycopersicon esculentum) is easy enough to grow in a backyard garden. But what about those tomato lovers who lack a yard and have only a balcony or patio on which to attempt a container veggie patch? Roma tomatoes, developed to have thick flesh good for cooking down into paste, are determinate growers, meaning they reach a genetically fixed size, but plants may still grow too large for some containers. Some growers may get around this dilemma by growing dwarf varieties, which are smaller plants but which still bear large fruit.

Best Container Sizes

Regardless of the type of tomato grown, a pot at least 14 inches across is the minimum size to have decent success growing a patio tomato. Pots with more than a 20-inch diameter help plants perform even better, and the deeper, the better. Five-gallon buckets with holes punched in the bottom or re-purposed half-barrels also work very well. All tomatoes, including standard and dwarf-sized Roma tomatoes, like to send their roots deep in search of water and nutrients, so provide as large and as deep of a container as possible for the tomato to give it plenty of room to roam. Although they are more expensive, terra-cotta or ceramic pots are heavier than more affordable plastic varieties and help to counteract any top-heaviness that might occur as a mature plant begins to set fruit.

Appropriate Varieties

Few varieties of Roma tomatoes have been developed for container growing. “Windowbox Roma” is one of the few readily available dwarf types, and can be grown in a pot as small as 14 inches and without any trellis-type support. Standard-sized Roma varieties will need as large a pot as is feasible, and should be planted with a trellis or stake for additional support. Unlike heirloom tomato varieties, determinate Romas bear their fruit all at once rather than over a prolonged harvest period.

Growing Medium Importance

Container growing differs a good deal from in-ground gardening. While regular garden soil works fine for plants in the ground, it almost never works when used in a pot. Earthworms and other tunneling creatures provide essential aeration in the ground. While in a pot, soil dug from the ground will simply become compacted with each watering and is difficult for roots to penetrate. Pot a containerized Roma tomato in a homemade or commercial mix consisting of a majority of composted pine bark with smaller but equal portions of peat moss and perlite or vermiculite. Other good materials to incorporate include coconut-based coir fiber, peanut shells and rice hulls. A large-pot formulation helps retain the proper amount of moisture between waterings and provides essential nutrients for the best plant performance.

Water, Water, Water

Container-grown Roma tomatoes will need more water, more often than garden-grown tomatoes. While the rule of thumb is to water in-ground tomatoes deeply but only once weekly, container tomatoes may require watering every day or even twice a day, especially in the summer months. Light shade in the hottest part of the afternoon can help reduce watering needs and prevent sun scorch on the leaves and fruit. If soil is still somewhat moist to the touch, the tomato probably does not need water. If the soil is dry to the touch or the plant is beginning to wilt, take emergency action. Flow as much water into the pot as it takes for the water to begin to pool on the surface of the soil. Allow water to drain through, and then repeat. Keep in mind when selecting a container for your Roma tomato that terra-cotta and ceramic pots will allow soil to dry out faster than plastic ones, so if you live in an area prone to hot and dry summers, a plastic container is a more water-conscious choice.

About the Author

Michelle Z. Donahue has worked as a journalist in the Washington, D.C., region since 2001. After several years as a government and economic reporter, she now specializes in gardening and science topics. Donahue holds a bachelor's degree in English from Vanderbilt University.